Synthesis, reactivity and structural characterization of ytterbium complexes bearing a tridentate [O,N,N] Schiff base ligand

The synthesis, characterization and reactivity of ytterbium monochloride supported by tridentate Schiff base ligands are described. The metathesis reaction of anhydrous YbCl₃ with 1 equivalent of the sodium salt of a Schiff base, {LNa(THF)}₂] (1) LH = 3,5-Bu^t₂-2-(OH)-C₆H₂CHN-8-C₉H₆N], gave the ytterbium Schiff base monochloride complex L₂YbCl (2). Complex 2 reacted with NaOAr (OAr = OC₆H₃Bu^t-2-Me-4) in a 1:1 molar ratio to form the desired aryloxo derivative L₂Yb(OAr) (3). Complex 3 can also be prepared by the one-pot reaction of the Schiff base HL, n-BuLi, YbCl₃ and NaOAr in a 2:2:1:1 molar ratio. However, an unprecedented ytterbium aryloxide LL′Yb(OAr) (4) (L′ = 3,5-Bu^t₂-2-(O)C₆H₂CH(C₄H₉)-NH-8-C₉H₆N) can be isolated in low yield as a byproduct in the later case. Reaction of complex 2 with 1 equivalent of (CH₂CH-CH₂)MgBr in THF afforded the unexpected complex Mg(H₂N-8-C₉H₆N)Cl(THF)₃]Br (5). Complexes 2-5 were fully characterized by elemental analysis and X-ray diffraction.